Add a feature layer from a portal item

Learn how to use an ArcGIS portal item to access and display a feature layer in a map.

You can host a variety of geographic data and other resources using ArcGIS Online. These portal items can also define how the data is presented. A web map or web scene, for example, not only defines the layers for a map or scene, but also how layers are symbolized, the minimum and/or maximum scales at which they display, and several other properties. Likewise, a hosted feature layer contains the data for the layer and also defines the symbols and other display properties for how it is presented. When you add a map, scene, or layer from a portal item to your app, everything that has been saved with the item is applied in your app. Adding portal items to your app rather than creating them programmatically saves you from writing a lot of code, and can provide consistency across apps that use the same data.

In this tutorial, you will add a hosted feature layer to display trailheads in the Santa Monica Mountains of Southern California. The hosted layer defines the trailhead locations (points) as well as the symbols used to display them.

Prerequisites

Steps

Open an Android Studio project with Gradle

1. To start this tutorial, complete the Display a map tutorial. Or download and unzip the Display a map solution in a new folder.

2. Modify the old project for use in this new tutorial. Expand More info for instructions.

   More info

   1. On your file system, delete the .idea folder, if present, at the top level of your project.

   2. In the Android tool window, open app > res > values > strings.xml.

      In the <string name="app_name"> element, change the text content to Add a feature layer from a portal item.

      strings.xml

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      <resources>
          <string name="app_name">Add a feature layer from a portal item</string>
      </resources>

   3. In the Android tool window, open Gradle Scripts > settings.gradle.kts.

      Change the value of rootProject.name to "Add a feature layer from a portal item".

      settings.gradle.kts

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      dependencyResolutionManagement {
          repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
          repositories {
              google()
              mavenCentral()
              maven { url = uri("https://esri.jfrog.io/artifactory/arcgis") }
          }
      }
      
      rootProject.name = "Add a feature layer from a portal item"
      include(":app")

   4. The UI theme composable in Display a map tutorial was DisplayAMapTheme. Rename the theme composable throughout the tutorial by refactoring DisplayAMapTheme.

      In the Android tool window, open app > kotlin+java > com.exmple.app > ui.theme > Theme.kt.

      Right-click the function name DisplayAMapTheme and select Refactor -> Rename. Replace the name with AddAFeatureLayerFromAPortalItemTheme.

      Theme.kt

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      @Composable
      fun DisplayAMapTheme(
      
          darkTheme: Boolean = isSystemInDarkTheme(),
          // Dynamic color is available on Android 12+
          dynamicColor: Boolean = true,
          content: @Composable () -> Unit
      ) {
          val colorScheme = when {
              dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
                  val context = LocalContext.current
                  if (darkTheme) dynamicDarkColorScheme(context) else dynamicLightColorScheme(context)
              }
      
              darkTheme -> DarkColorScheme
              else -> LightColorScheme
          }
      

   5. Click File > Sync Project with Gradle files. Android Studio will recognize your changes and create a new .idea folder.

3. If you downloaded the solution, get an access token and set the API key in MainActivity.kt.

   Instructions to set the API Key

   An API Key gives your app access to secure resources used in this tutorial.

   1. Go to the Create an API key tutorial to obtain a new API key access token using your ArcGIS Location Platform or ArcGIS Online account. Ensure that the following privilege is enabled: Location services > Basemaps > Basemap styles service. Copy the access token as it will be used in the next step.

   2. In Android Studio: in the Android tool window, open app > java > com.example.app > MainActivity.

   3. In the setApiKey() function, find the ApiKey.create() call and paste your access token inside the double quotes, replacing YOUR_ACCESS_TOKEN.

      MainActivity.kt

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          private fun setApiKey() {
      
              ArcGISEnvironment.apiKey = ApiKey.create("YOUR_ACCESS_TOKEN")
      
          }
      

Add import statements

In the Android tool window, open app > kotlin+java > com.example.app > MainScreen.kt. Replace the import statements with the imports needed for this tutorial.

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@file:OptIn(ExperimentalMaterial3Api::class)

package com.example.app.screens

import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.res.stringResource
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.PortalItem
import com.arcgismaps.mapping.Viewpoint
import com.arcgismaps.mapping.layers.FeatureLayer
import com.arcgismaps.portal.Portal
import com.arcgismaps.toolkit.geoviewcompose.MapView
import com.example.app.R

Add a feature layer to the map

You can reference an item (such as a web map or feature layer) hosted in a portal (such as ArcGIS Online) using its unique item ID. You will reference the Trailheads Styled feature layer stored in ArcGIS Online using its item ID: 2e4b3df6ba4b44969a3bc9827de746b3. You will then add that feature layer to your map's collection of data layers (operational layers).

1. In MainScreen, before the code that creates the ArcGISMap, create a new Portal referencing ArcGIS Online as the url parameter and Portal.Connection.Anonymous for the connection parameter.

   MainScreen.kt

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   fun createMap(): ArcGISMap {
   
       val portal = Portal(
           url = "https://www.arcgis.com",
           connection = Portal.Connection.Anonymous
       )
   
       return ArcGISMap(BasemapStyle.ArcGISTopographic).apply{
           initialViewpoint = Viewpoint(
               latitude = 34.0270,
               longitude = -118.8050,
               scale = 72000.0
           )
   
       }
   
   }

2. Then, create a PortalItem instance, passing portal and the id of the portal item that the feature layer will use.

   MainScreen.kt

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   fun createMap(): ArcGISMap {
   
       val portal = Portal(
           url = "https://www.arcgis.com",
           connection = Portal.Connection.Anonymous
       )
   
       val portalItem = PortalItem(
           portal = portal,
           itemId = "2e4b3df6ba4b44969a3bc9827de746b3"
       )
   
       return ArcGISMap(BasemapStyle.ArcGISTopographic).apply{
           initialViewpoint = Viewpoint(
               latitude = 34.0270,
               longitude = -118.8050,
               scale = 72000.0
           )
   
       }
   
   }

3. Next, create a FeatureLayer using FeatureLayer.createWithItem(), to which you pass the portal item.

   MainScreen.kt

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   fun createMap(): ArcGISMap {
   
       val portal = Portal(
           url = "https://www.arcgis.com",
           connection = Portal.Connection.Anonymous
       )
   
       val portalItem = PortalItem(
           portal = portal,
           itemId = "2e4b3df6ba4b44969a3bc9827de746b3"
       )
   
       val featureLayer = FeatureLayer.createWithItem(portalItem)
   
       return ArcGISMap(BasemapStyle.ArcGISTopographic).apply{
           initialViewpoint = Viewpoint(
               latitude = 34.0270,
               longitude = -118.8050,
               scale = 72000.0
           )
   
       }
   
   }

4. In the apply block for ArcGISMap, add the feature layer to the map.

   MainScreen.kt

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   fun createMap(): ArcGISMap {
   
       val portal = Portal(
           url = "https://www.arcgis.com",
           connection = Portal.Connection.Anonymous
       )
   
       val portalItem = PortalItem(
           portal = portal,
           itemId = "2e4b3df6ba4b44969a3bc9827de746b3"
       )
   
       val featureLayer = FeatureLayer.createWithItem(portalItem)
   
       return ArcGISMap(BasemapStyle.ArcGISTopographic).apply{
           initialViewpoint = Viewpoint(
               latitude = 34.0270,
               longitude = -118.8050,
               scale = 72000.0
           )
   
           operationalLayers.add(featureLayer)
   
       }
   
   }

5. Click Run > Run > app to run the app.

You should see a map of trail heads in the Santa Monica mountains. Double tap, Drag, pinch in, and pinch out on the map view to explore the map.

What's next?

Learn how to use additional API features, ArcGIS location services, and ArcGIS tools in these tutorials:

• Display a web map
• Display a web scene